1. Field of the Invention
The present invention relates to a wiper motor for driving a wiper.
2. Description of Related Art
A wiper motor of one previously proposed wiper system installed in, for example, a vehicle includes an automatic stop switch (an automatic stop mechanism for automatically stopping a wiper at a predetermined position). In this motor, even when a wiper switch is turned off to stop the wiper (the wiper having a wiper arm and a wiper blade), the wiper is not immediately, unconditionally stopped. Rather, upon turning off of the wiper switch, the wiper is moved to the predetermined position and is stopped there.
The automatic stop switch includes a movable plate (a movable contact) and a plurality of stationary contacts (stationary contact points). The movable plate is secured to a wheel gear of a speed reducing mechanism of the wiper motor and has a predetermined electrically conductive pattern. The stationary contacts are slidably engageable with the movable plate (the movable contact). Through connection/disconnection between the movable plate (the movable contact) and the stationary contacts, the power supply to the wiper motor is maintained through the automatic stop switch after the turning off of the wiper switch until the wiper is placed to the predetermined stop position.
Furthermore, one previously proposed wiper motor includes an intermittent drive circuit for intermittently driving the wiper (see Japanese Unexamined Patent Publication No. 2001-289286 corresponding to U.S. Pat. No. 6,410,849 B1). In order to intermittently drive the wiper, cooperation with the automatic stop switch is required. That is, a connection between the intermittent drive circuit and the stationary contacts is required. Thus, in Japanese Unexamined Patent Publication No. 2001-289286, a unit, which includes the intermittent drive circuit, is installed to an outer surface of a gear housing, which receives the wheel gear including the movable plate, to allow easy electrical connection between the intermittent drive circuit and the stationary contacts. In such a wiper motor, the electrical connection between the intermittent drive circuit and the stationary contacts is eased.
However, in the above wiper motor, the electrically conductive lines for connecting between power supply brushes of a motor main body and the automatic stop switch (the stationary contacts) and also the electrically conductive lines for supplying electric power to the brushes are installed as a separate connection unit on the outer surface of the gear housing. Thus, the number of components and the number of assembling steps are disadvantageously increased.
Furthermore, in the above wiper motor, an output shaft, which is supported by the gear housing and protrudes outward, is supported by a vehicle body in such a manner that the output shaft projects outward of the vehicle body through an installation opening formed in the vehicle body. In such a case, water (e.g., rain water droplets or car wash water) may possibly intrude into an interior of the vehicle body along the output shaft, possibly causing intrusion of the water into the gear housing. Thus, in the wiper motor of the above type, in which the unit having the intermittent drive circuit and the connection unit are provided on the outer surface of the gear housing, a separate protective measure is disadvantageously required to implement effective water resistance of the conductive lines.